Daniel Baker, director of the University of Colorado’s Laboratory for Atmospheric and Space Physics in Boulder, Colorado speculates that if there were no human VLF transmissions, the radiation boundary would likely stretch closer to Earth.

An artist's impression of the man-made 'bubble' surrounding earth, detected by NASASource:Supplied

“By understanding more about how VLF transmission helps shape our space environment, we learn more about this complex region surrounding us,” NASA said.

“The more we know, the more situational awareness we have to protect our satellites from natural radiation in space.”

By understanding more about how VLF transmission helps shape our space environment, we learn more about this complex region surrounding our planet, NASA says.Source:No Source

The twin Van Allen Probes were launched in 2012 to explore the radiation belts that surround Earth.

They’re specially designed to withstand the harsh bombardment of radiation they experience there.